1. Technical Field
The present invention generally relates to the art of semiconductor device and process and particularly, to a metal line structure and a manufacturing method for a trench.
2. Description of the Related Art
With the density of integrated circuit on semiconductor chips becoming more and higher, a resolution of photo-mask for defining patterns correspondingly is required to be increased, but due to the limit of wavelength range of exposure light source, the resolution of photo-mask has reached the extremity, accordingly the resolution of photo-mask is difficult to meet the requirements of the next generation integrated circuit except the wavelength of exposure light source can downwardly reduce. In order to solve such problem, a pattern being divided for light exposure by two photo-masks with relatively low resolutions and then combined to be a same layer structure for example a metal line structure nowadays has been a well-known scheme.
Generally, since the misalignment inevitably occurs during light exposure process, line joints respectively defined by two photo-masks would have an overlay area. However, since the overlay area of the two photo-masks would encounter twice etchings, over-etching would easily occur, which would cause some troubles in the subsequent process. Accordingly, how to overcome such drawbacks in the prior art is the major purpose of developing the present invention.